The pine shoot beetle, Tomicus piniperda, (L.) (Coleoptera, Scolytidae), is one of the most destructive insect pests affecting pines in its native range of Europe and Asia. In July of 1992, Tomicus piniperda was detected in Ohio, and by July of 1995, surveys showed that eight states (Michigan, Illinois, Indiana, Ohio, Pennsylvania, New York, Wisconsin and Maryland) and southern Ontario were infested. In Europe, Tomicus piniperda attacks Scots pine, Pinus sylvestris, but recent work in the U.S. has shown that it will shoot feed and breed in at least twelve species of hard and soft pines. Studies conducted in China demonstrated that this beetle has damaged eight pine species and caused serious economic losses in large areas of pine forest. In Sweden, the pine shoot beetle can cause 20% to 45% loss in yearly increment. In Poland, a loss of 36% in yearly increment was reported. A heavily infested Scots pine stand near Lockport, New York, has been experiencing 40%-60% loss in yearly increment since 1982. There is potential for significant economic damage by this insect in North America as well as continued losses in the Palearctic region.
Tomicus piniperda is a monogamous bark beetle species. It breeds in the cortical tissue of freshly cut or fallen timber, or very weakened trees. The mating season lasts for four to ten days in late March or early April in upstate New York. Females, which initiate host colonization, establish longitudinal galleries where they oviposit about 100-200 eggs. Development from the egg through the pupal stage lasts about two months. New adults emerge and fly to the tops of tree crowns where they mine and feed in the lateral shoots during the summer and early fall to become sexually mature. Each beetle can damage one to six shoots. Damaged shoots usually break and fall to the ground. After the first ground frost, in October or November, beetles exit the shoots and burrow under the bark at the base of healthy trees where they over winter. In milder climatic conditions some beetles overwinter in the shoots. In spring, soon after the snow melts around tree bases and the air temperature exceeds 10.degree. C., adult beetles start their breeding season. Tomicus piniperda normally have one generation per year, but 20% to 80% of beetles (depending on climatic conditions and food availability) can establish two broods that are separated by a short period of shoot feeding.
There has been considerable interest in the possible existence of an aggregation pheromone in Tomicus piniperda due to the economic significance of the insect. However, until now, field studies have failed to demonstrate its occurrence. It has been hypothesized that this species uses host volatiles to locate breeding substrate. The literature indicates that Tomicus piniperda is attracted to several monoterpenes isolated from Scots pine: .alpha.-pinene, 3-carene, and terpinolene. A synergistic effect of ethanol with the host monoterpenes has also been reported. Unfortunately, host compounds used as mass trapping lures have not been very effective. Therefore, there is a need for an attractant for Tomicus piniperda which is more effective than host compounds.